On
pages 67- 69, Ericsson explains that performing a strenuous physical
activity repeatedly can induce “an abnormal state for cells in some
physiological systems”(69), and that these biochemical states will
trigger the activation of dormant genes within the cell’s DNA.
Therefore, this frequent engagement in certain areas of practice
activities will induce physiological strain which will cause
biochemical changes that stimulate growth and transformation of
cells. Ultimately, there will be improved adaptations of the
physiological systems. Explain how Ericsson’s conclusion is valid
using your knowledge of gene regulation and of human cells. Use
section 6.3 and chapter 18 in Campbell for references. Relate to the
biology themes of regulation, evolution, and continuity and change in
your response.
Neil Edat (neil.edat@gmail.com)
Eleanor Maguire’s 1999 brain scans of London cabbies revealed greatly enlarged representation in the brain region that controls spatial awareness (67), a key skill for navigating the countless streets and turns of London. This expansion in brain size specifically in the region most utilized demonstrates the body’s amazing ability to adapt incredibly well to stresses. In the case of the taxi drivers, Driving in London is no easy task. The city’s long history creates a city with areas of poorly constructed roads serving as relics of the past. Finding one’s way around the city, a job London cab drivers make a profession out of, may overwhelm the untrained mind. The sheer number of quick corners, sudden sighs, and traffic signals is mind-boggling. This is the environment that London cabbies operate under day in and day out. In order to earn an adequate day’s salary, not only do these cab drivers need to survive the turmoil but they must thrive under it. This situation results in a recipe for adaptation: in-escapable environmental pressure. When the body’s options dwindle down to adapt or die, the body, being the strong, capable machine that it is, tends to choose adapt, especially under non-immediate life threatening circumstances as is in the cab driver situation. The constant demand cab drivers put on their brains for quicker retrieval of information and surrounding visualization is the “strenuous physical activity” mentioned by Ericson which triggers the “activation of dormant genes within the DNA” that facilitate growth of the body that will increase the cab driver’s physical/mental fitness to drive around London.
ReplyDeleteThe process of adaptation begins when physical stress caused by the demand for better performance sends a nervous system response that transforms into an endocrine system excretion of hormones such as GH from the anterior pituitary gland (http://en.wikipedia.org/wiki/Growth_hormone) or Epinephrine from the adrenal gland (http://en.wikipedia.org/wiki/Adrenaline). Both of these responses happen to better the organisms’ ability to survive under its current conditions and are triggered by immediate stimulants, in the case of epinephrine, or relatively long term external stimulants, in the case of GH. In the case of London cabbie brain growth, the environmental demands for better spatial visualization probably stimulated GH, the hormone for cellular reproduction, to be produced in the anterior pituitary cells, packaged and sent by the Golgi of those cells (Campbell 109) to travel along the blood stream to arrive at the cells of Entorhinal cortex of the brain, the area responsible for transforming sensory input from the environment and storing it as durable allocentric representations (http://en.wikipedia.org/wiki/Spatial_memory). Here the GH hormone will stimulate Gene Expression of proteins that enhance the size and function of the Entorhinal region by stimulating RNA polymerase to copy codons on the DNA, located within the nucleus of those cells, that encode for the desired proteins (Campbell 361). The successfully transcribed mRNA will then exit the nucleus membrane and be transported to membrane-bound ribosomes to create proteins that add onto size of the cell (Campbell 105). The proteins are created by combining the transcribed mRNA, tRNA floating around the cells, the membrane-bound ribosomes, and free-floating amino acids. The newly made protein will be used when the cell undergoes the G1 phase of the cell cycle by increasing its size to prepare for mitotic division into two separate cells (Campbell 231). The reoccurring of this process will produce multiple new cells and eventually noticeably expand the size of the Entorhinal cortex region of cab drivers’ brains.
The Gene Expression regulation using GH hormone to trigger mitosis is part of the Regulation theme and the Adaptation of cab drivers’ in terms of growth in brain size is part of the Evolutionary theme. If the situation was that cab drivers exclusively reproduced with other cab drivers, these adaptations could transform into evolution.